The present invention relates generally to pendulum or gate valve assemblies, and more particularly to a pendulum valve assembly including a new and improved arrangement providing both rotary and axial motion to a flapper of the pendulum valve assembly.
A pendulum valve assembly generally includes a housing containing a pendulum valve and including an interior space and a pair of openings through which gaseous fluid can enter and exit the interior space. Pendulum valve assemblies are particularly useful in high purity gas delivery systems, such as those used in semiconductor manufacturing or other thin film coating processes. As its name implies, a pendulum valve pivots between open and closed positions, and includes a valve body, which is usually provided as a disk or flapper, connected to a rotatably shaft by a pivot arm. In a completely opened position the disk of the pendulum valve is moved out of the flow path defined by the openings so that fluid can enter and exit the interior space of the housing, while in a completely closed position the disk is moved into sealing contact with a valve seat surrounding one of the openings so that fluid can not enter the interior space.
The movement of the disk usually requires rotational (i.e., pivotal or lateral) movement between the completely opened position and an intermediate position, and then at least some longitudinal (i.e., translational, linear or axial) movement from the intermediate position to the completely closed position where the disk is in sealing contact with the valve seat. In order to obtain this combination of rotational and translational movement, some prior pendulum valves have typically used multiple actuator elements.
In addition, in a xe2x80x9cstandardxe2x80x9d type gate or pendulum valve, as the gate starts to clear the opening of the valve housing, the gas flow increases rapidly. Also, since there is commonly an overlap between the gate and the opening (i.e., gate is a larger diameter than the opening), initial movement of the gate results in little if any change in flow. Thus, the overall conductance includes very little change in flow followed by a very rapid change in flow (and vice versa as the gate is closed), which results in poor control of flow (conductance) in this operating range of the valve.
U.S. Pat. No. 6,089,537 to Olmsted, which is assigned to the assignee of the present invention and incorporated herein by reference, discloses an improved pendulum valve assembly that uses a simple rotating cam mechanism that precisely controls the rotational and longitudinal movement of the valve body between a completely opened position and a completely closed position. U.S. Pat. Nos. 6,161,576, 6,328,051 and 6,409,149, which are all assigned to the assignee of the present invention and incorporated herein by reference, also disclose improved pendulum valve assemblies and systems.
What is further desired, however, is a new and improved pendulum valve assembly including a new and improved arrangement for providing both rotational and longitudinal movement of a disk of the valve assembly between a closed and an opened position. Preferably, a resolution of the longitudinal movement of the arrangement can be chosen independently of a resolution of the rotational movement. What is also desired, is a new and improved pendulum valve assembly that provides a more controllable and consistent change in conductance through the valve assembly during opening and closing of the valve.
The present invention provides a new and improved valve assembly including a housing having an interior space and an opening through which fluid can enter and exit the interior space, a valve body movable within the interior space between a completely opened position allowing fluid flow through the opening and a completely closed position preventing fluid flow through the opening, and a sleeve movable longitudinally along, and rotatably about, a longitudinal axis. The sleeve is connected to the valve body so that the valve body can rotate with the sleeve about the longitudinal axis between the completely opened position and an intermediate position where the valve body is substantially aligned with the opening but spaced longitudinally therefrom, and so that the valve body can move longitudinally with the sleeve between the intermediate position and the completely closed position.
One of the housing and the sleeve includes a cam surface, and the other of the housing and the sleeve includes a cam follower received by the cam surface. The assembly also includes a shaft extending along, and rotatable about the longitudinal axis of the sleeve, wherein the shaft is in screw-threaded engagement with the sleeve so that rotation of the shaft causes one of rotation and longitudinal movement of the sleeve with the cam follower.
Among other aspects and advantages of the present invention, the valve body of the valve assembly is provided with both rotational and longitudinal movement between the closed and the opened position. The valve assembly of the present invention also provides a resolution of the longitudinal movement that can be chosen independently of a resolution of the rotational movement of the valve body. Moreover, the present invention provides a new and improved pendulum valve assembly that supplies a more controllable and consistent change in conductance through the valve assembly during opening and closing of the valve.
Additional aspects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein exemplary embodiments of the present invention are shown and described, simply by way of illustration of the best modes contemplated for carrying out the present invention. As will be realized, the present invention is capable of other and different embodiments and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.